Cathedral Ceiling Installation - MHSC CDVR33 Installation And Operating Instructions Manual

CDV Series Gas Fireplace
3. Cut a hole in the roof using the locating hole as a center point. (Cover any exposed open vent pipes before
cutting hole in roof). The 9
length may be larger depending on the pitch of the roof. There must be a 1" minimum clearance from the vent
pipe to combustible materials. (Insulation should be considered a combustible material).
4. Connect a section of pipe and extend up through the hole.
NOTE: If an offset is needed to avoid obstructions, you must support the vent pipe every three (3) feet.
Use wall straps for this purpose. Refer to Figure 28, Page 23. Whenever possible, use 45° elbows instead
of 90° elbows. The 45° elbow offers less restriction to the flow of the flue gases and intake air.
5. Place the flashing over the pipe section(s) extending through the roof. Secure the base of the flashing to the
roof and framing with roofing nails. Be sure roofing material overlaps the top edge of the flashing. There must
be a 1" clearance from the vent pipe to combustible materials.
6. Continue to add pipe sections until the height of the vent cap meets the minimum building code require-
ments.
NOTE: You must increase vent height for steep roof pitches. Nearby trees, adjoining roof lines, steep
pitched roofs, and other similar factors may cause poor draft or down-drafting in high winds. Increasing
the vent height may solve this problem.
NOTE: If the vent pipe passes through any occupied areas above the first floor, including storage spaces
and closets, you must enclose pipe. You may frame and sheetrock the enclosure with standard construction
material. Make sure to meet the minimum allowable clearances to combustibles. Do not fill any of the
required clearance spaces with insulation.

CAThEDRAl CEIlING INSTAllATION

IMPORTANT: Review all information on previous
page before planning this installation. Cathedral
ceiling installations can be very tricky.
1. Remove shingles or other roof covering as neces-
sary to cut the rectangular hole for the support box.
Mark the outline of the cathedral ceiling support box
on the roof sheathing using the locating hole as a
center point.
2. Cut the hole 1/8" larger than the support box outline.
Figure 33.
3. Lower the support box through the hole in the roof
until the bottom of the box extends at least 2" ( mm)
below the ceiling. See Figure 33. Align the support
box vertically and horizontally using a level. Tem-
porarily tack the support box in place through the
inside walls and into the roof sheeting.
4. Using tin snips, cut the support box from the top
corners down to the roof line and fold the resulting
flaps over the roof sheeting. See Figure 34. Apply a
bead of non-hardening mastic around the top edges
of the support box to make a seal between the box
and the roof. Nail in place with roofing nails. Remove
any combustible material that might be inside the
support box.
5. Complete the cathedral ceiling installation by follow-
ing the same procedures outlines in steps 2 through
6 for Flat Ceiling Installation, page 25 and above.
26
1 / "x9 1/ 2 " (241 mm x 241 mm) hole must be measured on the horizontal. Actual
2
Cut Hole 1/8"
Larger than
Support Box when
Projected onto
Roof line.
Figure 33 - Cathedral Ceiling Support Box
Figure 34 - Installed Cathedral Ceiling
Support Box
VENT INSTAllATION
Cathedral
Level
Ceiling
Support Box
2" Minimum
Finished
Installation
Apply Non-hardening
Mastic Under all Edges
of Support Box before
Nailing
Below
Ceiling
69D0023